Startup Says It’s the First to Make Synthetic Spider Silk

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Startup Says It’s the First to Make Synthetic Spider Silk

Engineered spider silk fibers spinning on a roller.

Bolt Threads

For years, materials scientists have been trying to figure out a way to give consumers broad access to the benefits of spider silk. As a naturally occurring supermaterial, spider silk is five times stronger than steel and more elastic than rubber bands, which suggests some amazing potential use cases, including bulletproof vests, biodegradable water bottles, and flexible bridge suspension ropes. But so far, every group that’s attempted to produce enough of the stuff to bring it to the mass market, from researchers to giant corporations, has pretty much failed.

The problem is there’s no way to get the silk from spiders themselves—creatures known to be territorial and cannibalistic, which doesn't lend itself to raising them in groups. So people have had to resort to creative workarounds. They’ve tried raising genetically engineered silkworms, or inserting genes into microorganisms to express the needed spider silk protein. All of these efforts, however, have seen little success. Spider silk protein is complex, and even when experimenters are able to create fibers, these come out so fine that entirely new spinning systems need to be invented from scratch to turn the strands into thread. It doesn’t keep groups from trying though, and every few months or so, it seems, news of some spider silk breakthrough goes viral, only to quiet down after a few months. And consumers keep waiting.

The fibers can even be tuned to possess different properties on demand: the researchers simply change the protein sequence.

But today, after five years of quiet operation, a startup called Bolt Threads has emerged to claim it’s made meaningful progress on the challenge. The Emeryville, California-based company grew out of the graduate school studies of three scientists from the University of California, San Francisco and UC Berkeley, and it has raised $40 million so far from such notable investors as Foundation Capital, Formation 8 and Founders Fund, as well as from government grants from institutions like the National Science Foundation. If its founders are to be believed, Bolt Threads may have solved the mystery—finally—of how to make spider silk commercially plausible.

“Basically, our mission from the beginning was to make a scalable amount of spider silk and bring that to consumers,” CEO Dan Widmaier tells WIRED. “It’s a problem that’s been around for a long time, and has been hampered entirely by technical challenges.”

Widmaier knows it’s a bold claim. That’s why, he says, the company chose to fly under the radar for so long. “We decided to keep our heads down and try to solve the problem before we went out and started talking about all the cool things we can do with the technology,” he says. “Now, we’re ready to say we’re here.”

Engineered spider silk fibers being extruded from a spinneret into a liquid bath.

Bolt Threads

Making Spider Silk Without Spiders

Widmaier says that generally speaking, what they do isn’t new in the world of biotechnology. The scientists genetically engineered a microorganism that can yield large quantities of silk protein through a yeast fermentation process—not just grams of silk protein, but metric tons. Then, using a proprietary mechanical system, a wet silk protein solution is manually squeezed through small extrusion holes and goes into a liquid bath that turns the stuff into solid fibers. While Widmaier won't give away the minute specifications of how it all works, he does say that the extrusion process mimics the behavior of a spider’s spinneret—its silk-spinning organ. The naturally occurring spinning process has been the other key problem would-be spider silk producers have had difficulty mimicking in the past.

The result, Widmaier claims, is a technology that can artificially recreate the remarkably strong protein fibers spiders make. On top of that, he says, the fibers can even be tuned to possess different properties on demand: the researchers simply change the protein sequence on the platform to tweak the qualities of the material according to preference. Widmaier says they can make spider silk that’s stronger, stretchier, or waterproof, for example, depending on preference. “What we’ve learned is we could prod nature a little bit in the lab and engineer these new properties in,” says Widmaier.

"That forms a kind of platform where we are able to design for material property as well as scale up our manufacturing at a good price point, so we can commercialize it."

Better, Cheaper, Faster

There's not too many people to meet in Bolt Threads' laboratory, a 33,000-square-foot space on the fourth floor of a squat building right off the I-80 highway in Emeryville. (Widmaier says the fermentation team is off on a training trip in Michigan.) When I come for a visit on a recent afternoon, a copy of E.B. White's Charlotte's Web is* *resting on a table by the lobby couches. A ceiling-to-floor art panel with Bolt Threads' primary amino acid sequence for its engineered silk is displayed amongst a cluster of conference rooms named after different textiles: lace, velvet, silk, gingham, poplin and tweed.

Widmaier takes me through the lab spaces, which are separated according to the different phases of the team's spider silk production. There's a room for researchers to do cell biology experimentation; several spaces where big and small fermentation tanks sit, slowly yielding silk protein; and a room where the actual fibers are spun and dried. In the fiber analytics room, strands of silk are stretched out and taped onto black sheets of paper, then catalogued according to the properties the researchers have observed in them. I ask Widmaier whether they have actual samples of fabric I can touch, and he responds that they do, but they haven't found them since they disappeared into boxes when the company moved into their more spacious digs in January.

Studying chemical biology at UCSF before starting Bolt in 2010, Widmaier was spending a big chunk of his time looking into the question of how to make lots of spider silk cheaply. Bolt's chief scientific officer, David Breslauer, meanwhile, was earning his bioengineering doctorate at UC Berkeley researching microfluidic devices—work that translated nicely into Bolt Threads' proprietary spinning systems. Vice President of Operations Ethan Mirsky, meanwhile, worked in the same lab as Widmaier at UCSF and had experience working in the startup scene in a past life. The students' advisers connected the scientists, and they began to collaborate on research for a few of years, before the idea of forming a company ever emerged.

But the group ultimately realized that there was great commercial potential in their research. "We had the commercial pieces pretty well fleshed out on a theoretical level, and we just had to build the platform," Widmaier says.

Widmaier says it was a lucky break that Bolt Threads happened to come together as the barriers in biotechnology came way down. "Compared to decades ago, the tools are better, cheaper and faster," he says. "We were on the cutting edge of a lot of these technologies, and we were riding the wave in the right direction."

Spider Silk iPad Covers

According to Sam Hudson, a professor of polymer chemistry at North Carolina State University who's familiar with Bolt Threads' process as one of the company's third-party advisors, the real innovation is developing a fermentation system that can produce large quantities of silk protein that can be isolated. "The fibers are 100 percent silk protein," he says. "I'm not aware of anybody else who's been able to make this much progress on the problem."

Bolt Threads says it expects to launch its first commercial textiles by next year. But these won't just be niche products for niche industries, according to its founder. Widmaier envisions that Bolt Threads' fabrics could be in things like iPad covers and car seats—things that consumers actually see and touch every day.

That's because, at least according to Widmaier, not only has his team decoded how to produce spider silk but the process for making it into customizable textiles for those everyday things. Your iPad cover could one day be certifiably waterproof; perhaps your next jacket could be bulletproof. And the production process is cheap enough that the those products will be affordable. In the next few months, Bolt Threads says it plans to explore creating its own line of consumer products, as well as partner with other textile manufacturing operations.

"After figuring out we could make [spider silk], the next thing we wanted to know was: could you make enough of it to do something interesting?" Widmaier says, "Now we want to create products that people would meaningfully benefit from."